Organic materials



Patented Aug. 22, 1939 UNITED STATES ORGANIC MATERIALS Henry Dreyfus, London, England No Drawing. Application March 18, 1938, .Serial No. 196,629. In Great Britain April 15,

3 Claims.

This invention relates to the treatment of or-' ganic materials, and in particular to the saponification of filaments, fibres, yarns, ribbons, fabrics,

films and like materials having a basis of cellu- 5 lose acetate or other organic ester of cellulose.

I have found that N-alkyl and aralkyl cyclohexylamines are particularly valuable saponifying agents for organic esters of cellulose. Thus, for example, by treatment of cellulose acetate yarn in an aqueous bath containing N-methylcyclohexylamine, deep-seated saponification of the material can be effected, accompanied by an increase in extensibility with substantially no decrease in tenacity. The material may also in this way acquire an aflinity for cotton dyes.

Among the saponifying agents of the invention, monoalkyl substitution products in which the alkyl group is of low molecular weight, for example, methyl-, ethyl-, propyl-, isopropyland n-butyl-,

and secondary butyl-cyclohexylamines, are of particular value. Di-substituted derivatives, however, for example dimethyl and diethyl cyclohexylamine and aralkyl cyclohexylamines such as benzyl cyclohexylamine are also of value provided the molecular weight is not unduly increased by the substitution. Substitution products of considerably higher molecular weight than cyclohexylamine itself, for example dibutyl, hexyl, octyl and dibenzyl cyclohexylamine, lack the striking effect on extensibility of similar products of lower molecular weight.

The saponifying agents of the inventionare preferably applied to the materials in an aqueuos bath. The materials may be drawn continuously through the saponifying bath in yarn or fabric form or saponification may be conducted as a batch process. The materials in fabric form or as yarn in hank form or wound on foraminous package carriers may be immersed in the bath until the desired saponification has been eifected.

Saponification may be conducted under atmospheric pressure but it is of advantage to carry out the process at super-atmospheric pressure, for example under pressure of 5-10 or more pounds per square inch. The temperature may range from 20-30 C. or even less, up to 70 or 80 C. or more according to the concentration of the bath.

Although the use of aqueous baths is preferable, j

saponification may be eifected in non-aqueous 5o baths containing a suitable'source of hydroxyl ions, for example in an alcoholic mediumpor" alcoholic baths are apt to have too strong a swelling action on the materials treated. The swelling action of the saponifyiug bath may be controlled by the addition to the bath of agents having a swelling repressing action such as are 5 described for example in U. S. Patent No. 2,091,972. To facilitate subsequent recovery from the saponifying bath the swelling repressing agent may bea salt formed in the saponification,

for example where the saponifying agent is methyl 10 cyclohexylamine, an appropriate proportion of methyl cyclohexylamine acetate may be added to the bath before saponification. During saponification the concentration of the saponifying agent or of any swelling repressing agent present in the 15 bath may be maintained substantially constant; or the concentration of the saponifying agent may be allowed to decrease during saponification.

With a view to obtaining materials of high tenacity, it is of advantage that the materials treated should have been stretched considerably at some stage in their manufacture. They may, for example have been highly stretched during their formation by a wetspinning process in which stretch-assisting agents are present in the coagulating bath, or under the influence of an organic softening liquid or steam or hot water after their production. The materials may have undergone a shrinking operation after stretching.

The degree of saponification effected will depend to some extent upon the object of the process; whether, for example, it is required merely to impart to the materials an amnity for cotton dyes, or to increase their tenacity, or to produce 35 materials consisting substantially of regenerated cellulose. The degree of saponlflcation may, for example, reduce the original acid radicle content by 15 .-20% or less, or may be more extensive involving a reduction of 25 or 30 up to 40 or .or from to or or may even effect substantially complete removal of the acid radicle groups. By the process of the invention it is possible to obtain a deep-seated saponiflcation extending to a considerable depth beneath the 5 surface of the materials or even throughout substantially the whole section of the material.

The following example illustrates the invention:

The material is then removed from the bath, Washed and dried.

Lower concentrations of the base may be used at higher temperatures, for example, a 12% solution may be used at temperatures between and C.; or the concentration of the base may be increased and saponification efiected at a lower temperature.

Although the invention has been described with particular reference to the saponification of filaments, threads, ribbons, fabrics, films and like materials of cellulose acetate, it is also applicable to the treatment of materials comprising other esters of cellulose, i.e., esters containing organic acidyl groups, for example simple esters such as cellulose iormate, propionate or butyra'te, etheresters, such as ethyl cellulose acetate and oxyethyl cellulose acetate, and mixed esters, such as cellulose acetate-propionate, cellulose acetatepropionate-butyrate and nitrocellulose acetate. The cellulose acetate or other base of which the materials to be saponified are made may be 01 high, medium, or low viscosity. For example, in the case of cellulose acetate the viscosity may be above 30 to 50 or even or more, measured by comparing the viscosity of a 6% solution of the cellulose acetate in acetone at 25 C. with that of glycerine at the same temperature, taken as 100; or may be considerably lower, for example 10 or 15 to 20, on the same scale.

Having described my invention, what Lqiesire to secure by Letters Patent is- 1. Process for improwng the properties of materials comprising filaments, fibres, yarns, ribbolus and the like having a basis of organic esters of cellulose comprising saponifying said materials by treatment under superatmospheric pressure with a bath containing 4-5% of a cyclohexylamine derivative of the formula CH; C I la R CH-N where R1 is an alkyl or aralkyl group and R2 is an alkyl or aralkyl group or a hydrogen atom.

2. Process for improving the properties of materials comprising filaments, fibres, yarns, ribbons and the like having a basis of cellulose acetate which comprises saponifying said materials by treatment under superatmospheric pressure with an aqueous bath at a temperature between 35 and 50 C. and containing 4-5% N-methyl cyclohexylamine.

3. Process for improving the properties of materials comprising filaments, fibres, yarns, ribbons and the like having a basis of cellulose acetate which comprises saponifying said materials by treatment under superatmospheric pressure with an aqueous bath at a temperature between 35 and 50 C. and containing 4-5% N-benzyl cyclohexylamine.

HENRY DRE'YFUS. 

